Fluid Motion Past a Porous Circular Cylinder With Initial Pressure Gradient

1980 ◽  
Vol 47 (3) ◽  
pp. 489-492 ◽  
Author(s):  
J. L. Gupta
Keyword(s):  
Circular Cylinder ◽  
Pressure Gradient ◽  
Drag Force ◽  
Asymptotic Expansions ◽  
Fluid Motion ◽  
Initial Pressure ◽  
Matched Asymptotic Expansions ◽  
Two Dimensional ◽  
Dimensional Flow ◽  
Two Dimensional Flow

The problem of two-dimensional flow, past a porous circular cylinder, with initial pressure gradient is solved using the method of matched asymptotic expansions. It is found that the drag force experienced by the cylinder is increased due to initial gradient although it remains smaller than the drag force experienced by an identical impervious body.

Pressure Distributions and Forces on Rectangular and D-shaped Cylinders

1972 ◽  
Vol 23 (1) ◽  
pp. 1-6 ◽  
Author(s):  
B R Bostock ◽  
W A Mair
Keyword(s):  
Boundary Layer ◽  
Circular Cylinder ◽  
Drag Coefficient ◽  
Pressure Distribution ◽  
Two Dimensional ◽  
Dimensional Flow ◽  
Pressure Distributions ◽  
Two Dimensional Flow ◽  
Rectangular Cylinders ◽  
Shaped Section

SummaryMeasurements in two-dimensional flow on rectangular cylinders confirm earlier work of Nakaguchi et al in showing a maximum drag coefficient when the height h of the section (normal to the stream) is about 1.5 times the width d. Reattachment on the sides of the cylinder occurs only for h/d < 0.35.For cylinders of D-shaped section (Fig 1) the pressure distribution on the curved surface and the drag are considerably affected by the state of the boundary layer at separation, as for a circular cylinder. The lift is positive when the separation is turbulent and negative when it is laminar. It is found that simple empirical expressions for base pressure or drag, based on known values for the constituent half-bodies, are in general not satisfactory.

Steady two-dimensional viscous flow in a jet

1972 ◽  
Vol 55 (1) ◽  
pp. 49-63 ◽  
Author(s):  
K. Capell
Keyword(s):  
Point Source ◽  
Viscous Flow ◽  
Closed Form ◽  
Stream Function ◽  
Asymptotic Expansions ◽  
Far Field ◽  
Two Dimensional ◽  
Complete Structure ◽  
Dimensional Flow ◽  
Two Dimensional Flow

An idealized two-dimensional flow due to a point source ofxmomentum is discussed. In the far field the flow is modelled by a jet region of large vorticity outside which the flow is potential. After use of the transformation\[ \zeta^3 = (\xi + i\eta)^3 = x + iy, \]the equations suggest naively obvious asymptotic expansions for the stream function in these two regions, namely\[ \sum_{n=0}^{\infty}\xi^{1-n}f_n(\eta)\quad {\rm and}\quad\sum_{n=0}^{\infty}\xi^{1-n}F_n(\eta/\xi) \]respectively. Consistency in matching these expansions is achieved by including logarithmic terms associated with the occurrence of eigensolutions.Fnis easy to find andJncan be found in closed form so the inner and outer eigensolutions may be fully determined along with the complete structure of the expansions.

On the drag of two-dimensional flow about a circular cylinder

2004 ◽  
Vol 16 (10) ◽  
pp. 3828-3831 ◽  
Author(s):  
C.-Y. Wen ◽  
C.-L. Yeh ◽  
M.-J. Wang ◽  
C.-Y. Lin
Keyword(s):  
Circular Cylinder ◽  
Two Dimensional ◽  
Dimensional Flow ◽  
Two Dimensional Flow

Axisymmetric turbulent boundary layer along a circular cylinder at constant pressure

1976 ◽  
Vol 74 (1) ◽  
pp. 113-128 ◽  
Author(s):  
Noor Afzal ◽  
R. Narasimha
Keyword(s):  
Boundary Layer ◽  
Circular Cylinder ◽  
Turbulent Boundary Layer ◽  
Constant Pressure ◽  
Axisymmetric Flow ◽  
Universal Constant ◽  
Two Dimensional ◽  
Dimensional Flow ◽  
Flow Experiment ◽  
Two Dimensional Flow

A constant-pressure axisymmetric turbulent boundary layer along a circular cylinder of radiusais studied at large values of the frictional Reynolds numbera+(based upona) with the boundary-layer thickness δ of ordera. Using the equations of mean motion and the method of matched asymptotic expansions, it is shown that the flow can be described by the same two limit processes (inner and outer) as are used in two-dimensional flow. The condition that the two expansions match requires the existence, at the lowest order, of a log region in the usual two-dimensional co-ordinates (u+,y+). Examination of available experimental data shows that substantial log regions do in fact exist but that the intercept is possibly not a universal constant. Similarly, the solution in the outer layer leads to a defect law of the same form as in two-dimensional flow; experiment shows that the intercept in the defect law depends on δ/a. It is concluded that, except in those extreme situations wherea+is small (in which case the boundary layer may not anyway be in a fully developed turbulent state), the simplest analysis of axisymmetric flow will be to use the two-dimensional laws with parameters that now depend ona+or δ/aas appropriate.

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